Both various components of motor vehicles and containers for particular contents or use locations are required to have certain antistatic properties in their particular application in order to counter possible risks of explosion. Plastic parts and plastic containers have a disadvantage here compared with metal parts since the plastic as such does not conduct electrical current and is therefore unable to eliminate the electrical charges formed on surfaces, which is no problem for metals owing to their electrical conductivity. All conventional measures hitherto for improving the antistatic properties of plastic components are associated with disadvantages in other areas.
Antistatics added to plastics as an additive only act on the surfaces of the plastic walls in combination with moisture. They have no action if moisture does not reach the wall, and they entail the risk of entering the contents due to diffusion and contaminating the latter.
A known aid for, for example, rendering plastic tank fill necks antistatic consists of a wire spoke suspended in the plastic necks. It is connected to the tank cap and thus to the metal body, and consequently any electric charge which arises can be eliminated. In this procedure, problems consist in the time-consuming retrofitting of the metal spoke in the tank fill neck system, which otherwise consists entirely of plastic and is assembled by plastic joining methods.
Another variant consists in making the fill neck out of a plastic which is highly filled with electrically conductive carbon black. This makes the plastic wall itself conductive. Problems consist here in the reduced toughness of the plastic due to the high level of filling, which is reflected in impaired impact strength of the fill neck.
Corresponding carbon black-filled material grades are used for the production of antistatic canisters. Besides the reduced shock resistance, problems are also caused by the relatively poor weldability of the material, which results in poor pinch-off weld strengths in the canisters typically produced by blow moulding. The same applies in coextruded containers having a conductive inside layer, in which the pinch-off weld is likewise typically formed from material of the inside layer.
Especially in the case of so-called intermediate bulk containers (IBCs), i.e. large-volume containers which consist of an inner plastic container and an outer support device, usually of metal, and which are used for the transport and storage of liquid or powder-form chemicals, antistatic properties are produced by particularly close contact of the plastic with metal surfaces or external coating with a conductive material. However, problems consist here in the high consumption of material and/or additionally necessary working steps during manufacture.